Regenerative braking is an energy recovery mechanism that is used to decelerate a vehicle by converting its kinetic energy into another form of energy, for example electrical energy. The conversion of the kinetic energy to electrical energy provides a braking effect. The recuperated energy may then be stored, for example in a battery, for use at a later stage.
The powertrain of vehicles, such as electric vehicles or hybrid vehicles, may comprise one or more electric motors. In a common type of regenerative braking, the electric motors may be operated as generators during braking, the output from which may be supplied to an electrical load of the vehicle. Additionally and/or alternatively, the output from the generator may be supplied to an energy storage device for subsequent use in powering the electrical loads, vehicle components with high power requirements and/or a propulsion system of the vehicle, for example.
During the operation of hybrid vehicles, for example mild hybrid vehicles, it is desirable to maximize the regenerative braking during deceleration of the vehicle, which may be due to, for example, the release of the accelerator pedal. However, in maximizing the regenerative braking during accelerator pedal lift-off, the rate of deceleration of the vehicle may appear unexpectedly high to the driver of the vehicle.
These increased levels of deceleration, which may for example be experienced in vehicles comprising a 10 kW electrical motor, create an impression of inefficiency and a lack of ability to coast the vehicle. Furthermore, unexpected deceleration on accelerator pedal release may cause the driver to operate the vehicle in a less efficient manner, which may be detrimental to the customer's perception of the drivability and associated economy of a hybrid system.